The 15-year-old Gauff on Saturday became the youngest player to reach a WTA final since Czech Republic's Nicole Vaidisova won the Tashkent Open in 2004, also aged 15.

Gauff only made it to the main draw of the event as a lucky loser but has made her opportunity count with a barnstorming run to Sunday's final, where she will meet former French Open champion Jelena Ostapenko.

The American faced 10 break points but recovered well to fend off nine of them against Petkovic in the semi-final, before sealing victory on her second match point.

"This is crazy," Gauff said.

"I thought I was out in qualifying and now I'm here.

"Linz is my special place.

"This was one of the highest-level matches I've played. Andrea hit a lot of winners and put pressure on me.

"I was fighting for every point, even at break points down, I just tried to get the serve in and make her play a point."

Gauff's popularity has soared since she became the youngest player to qualify for the Wimbledon main draw in the professional era and reached the fourth round in July, beating seven-times grand slam champion Venus Williams along the way.

She also enjoyed the home support at the US Open before falling to Naomi Osaka in the third round.

Having dropped just one set in her main draw matches in Linz this week, Gauff has already ensured a place in the top 100 when the new WTA rankings are released on Monday.

Australian Associated Press